Steam generator

ABSTRACT

The generator has a handle part  3  secured to it by screws (not shown) inserted from below the lower casing  2.  The handle part has a handle per se  4,  which is of U cross-section for accommodating a handle  21  of a hose  22.  The hose handle has a resilient button  23  which is received in an aperture  5  in the handle part  3,  for retaining the hose handle in place, when not in use. Beneath the handle  4  is an opening  11,  covered by a cover plate  12.  The plate has depending lugs  14,  which are disengageable by lateral finger pressure via cut-outs  15.  Removal of the cover plate opens an aperture  31  in a water reservoir  32.  The water reservoir has a filling spout  33.  The connector moulding  35  has two bored-through projections  40,41.

The present invention relates to a steam generator, particularly though not exclusively for use in steam cleaning.

Domestic steam cleaners are known. For instance, Italian utility model No GE99U27 of 30^(th) Jul. 1999, shows apparatus having a body containing a boiler and provided with a handle fashioned to receive a distal end of a hose for delivering steam from the boiler, when not in use. The production version of this cleaner has a valve accommodated in the handle for releasing steam into an appliance carried on the handle.

This design results in the hose being fully pressurised up to the handle whenever the valve is not open for release of steam. Apart from any adverse safety implications, this design at least requires the use of constant pressure resistant hose from the boiler to the handle.

The object of the present invention is to provide an improved steam generator.

According to the invention there is provided a steam generator comprising:

a water reservoir;

a pump for pumping water from the reservoir

a flash steam boiler for boiling water pumped from the reservoir to produce steam;

a steam supply hose leading from the boiler;

a handle at the distal end of the hose; and

means on the handle for activating the pump, to cause a flow of steam from the distal end of the hose.

The pump activating means may be an electrical switch, where the pump is an electrical pump as is normal. However from safety considerations, the pump activating means is preferably non-electric, or at least is adapted to send a non-electrical signal to a switch for switching electrical power to the pump. Conveniently the activating means is adapted to send a pneumatic signal to the pump switch.

In the preferred embodiment, the activating means on the handle is a manually operated pneumatic system. It is envisaged that a small bellows device could be employed for activation. However, we prefer to use a piston and cylinder on the handle and a bellows for actuating a microswitch in a body of the generator. We have noted that under certain circumstances, particularly when the apparatus is thoroughly warmed, the pneumatic activating system, including a pipe to the switch, becomes over-pressurised above the pressure resulting from activation, such that release of manual pressure does not result in the expected release of pressure in the pipe. Accordingly it is preferred that the pneumatic activating device is arranged to be normally open to atmosphere when in the quiescent state. Again, the activating device can be a bellows device, with an aperture closed on activation. However, the preferred activating device is a piston and cylinder device having a counter-bore at its end remote from the electrical switch, the arrangement being such that the piston is out of pneumatic sealing of the cylinder in its quiescent state, hence releasing any over-pressure.

Preferably the flash steam boiler incorporates a first thermostatic controller for switching an electrical heater for the boiler—ON at a lower temperature and OFF at a higher temperature. These temperatures are preferably tens of Centigrade degrees apart, with the lower temperature being tens of degrees above 100° C. In the preferred embodiment, the lower temperature is approximately 140° C. and the upper temperature is approximately 175° C.

Further the boiler preferably includes a second thermostatic controller for inhibiting operation of the pump until the boiler is at or close to its operating temperature or at least the lower of the temperatures of the first thermostatic controller. Preferably the second thermostatic controller is adapted to maintain the pump switch OFF until the boiler is a temperature tens of Centigrade degrees above 100° C. but lower than the lower temperature of the first thermostat. In the preferred embodiment, the boiler inhibition temperature is approximately 130° C. As an alternative to the provision of the second, pump-inhibition thermostatic controller, the pump can be arranged to be inhibited below the lower temperature of the first thermostatic controller.

Preferably the boiler includes a third thermostat for isolating the boiler in the event of the temperature of the boiler reaching a temperature tens of Centigrade degrees above the higher temperature of the first thermostat. In the preferred embodiment, the boiler isolation temperature is approximately 225° C.

The preferred boiler is structured with a central, cylindrical chamber divided longitudinally by a dividing tongue. A water inlet is provided on one side of the tongue and a steam outlet is provided at the other side, the inlet and outlet being at one end of the tongue and communication around the tongue being provided at the other end of the tongue. A further safety valve outlet, is preferably provided.

The preferred safety valve is an obturator in an elastomeric tube connected to the safety valve outlet, the tube being vented on the side of the obturator remote from the safety valve outlet. Over-pressure steam is vented on expansion of the tube around the obturator, allowing the steam to flow past the obturator.

Preferably the wattage of the boiler and the capacity of the pump are matched whereby the pump delivers no more water than the boiler can continuously evaporate. In the preferred embodiment, the boiler is rated at 2000 Watts and the pump is adapted to deliver 1.6 cubic centimetres per second of water.

The preferred pump is a mains frequency diaphragm pump.

Preferably, the steam generator includes:

a casing for the pump and the boiler,

a casing handle formed to receive releasably the hose handle and

release means on the hose handle, discrete from the pump activation means, for releasing the hose handle from the casing handle.

In the preferred embodiment, the steam generator includes a caddy, the caddy and the casing being formed complementarily for accommodation of the caddy on the casing and a latch preferably being provided for normally retaining the casing on the caddy.

Normally, the steam generator will be provided in combination with one or more steam application tools and/or one or more hose extensions, the tool(s) and the hose extension(s) being formed:

in like manner to the casing handle to receive releasably the hose handle and

with an inner steam connection socket, held connection with a steam connector on the handle, whilst a respective one of the tool(s) and the hose extension(s) receives the hose handle.

The hose extensions can have double walls, with an air gap between an outer wall and an inner steam conduit:

the outer wall having

-   -   release means in like manner to the release means on the hose         handle and

the inner steam conduit having

-   -   the inner steam connection socket at one end and     -   a steam connector at the other end, also in like manner to the         steam handle for connection to another extension or tool.

Preferably the caddy has both a compartment for storage of the tool(s) and respective receptacle(s) for the hose extension(s), the receptacle(s) being formed in like manner to the casing handle to receive releasably the extension(s) with their release means. Further the caddy can have a socket for upright support of the hose extension(s), whereby an item of clothing can be supported therefrom for steaming.

The casing also can have a compartment for storage of auxiliary tools adapted to connect to the hose without use of the release means.

Preferably the water reservoir is detachable from the casing for filling with water, a latch being preferably provided for retaining the reservoir on the casing. Also the reservoir is preferably provided with a sealable lid whereby the generator can be used at varying orientations the latch being integrated with the sealable lid.

To help understanding of the invention, a specific embodiment thereof will now be described by way of example and with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a steam generator according to the invention;

FIG. 2 is a similar view of the generator, with a top cover removed;

FIG. 3 is a view of the components shown in FIG. 2, from the other side and other end;

FIG. 4 is a perspective view of a flash steam boiler of the generator;

FIG. 5 is a view similar to FIG. 4 of the boiler with an end plate removed;

FIG. 6 is a similar view of the end plate;

FIG. 7 is a perspective view of a hose handle of the steam generator;

FIG. 8 is a similar view of the handle with a cover part removed;

FIG. 9 is a view similar to FIG. 1 of a caddy for the steam generator of FIG. 1;

FIG. 10 is a plan view of the caddy of FIG. 9;

FIG. 11 a perspective view of a rigid steam hose extension;

FIG. 12 is a cross-sectional side of the rigid steam extension hose of FIG. 11;

FIG. 13 is a side view of a steam tool attached to the hose handle of the steam generator;

FIG. 14 is a view similar to FIG. 13 of the hose handle with a smaller auxiliary tool fitted; and

FIG. 15 is a cross-sectional view of an alternative activation device.

Referring to the drawings, the steam generator there shown will now be described. Please note that for ease of description and understanding of how the steam generator is constructed, the description does not follow the order of the features of the statement of invention set out at the beginning of this specification.

Most parts of the generator are plastics materials injection mouldings.

The generator has a two-part, upper and lower, casing 1,2. The upper casing 1 has a generator handle part 3 secured to it by screws (not shown) inserted from below the lower casing 2. The handle part has a handle per se 4, which is of U cross-section for accommodating a handle 21 of a hose 22. The hose handle has a resilient button 23 which is received in an aperture 5 in the handle part 3, for retaining the hose handle in place, when not in use. Beneath the handle 4, the upper casing is recessed 6 to provide finger access. Behind the recess is a double aperture 7 for LED indicators 8,9 and a further aperture (not visible in FIG. 1) for an ON/OFF switch 10. Behind these apertures is an opening 11, covered by a cover plate 12. The plate has depending lugs 14, which are disengageable by lateral finger pressure via cut-outs 15. Removal of the cover plate opens an aperture 31 in a water reservoir 32—described in more detail below.

At the joint line 16 between the upper and lower casings, a rebate 17 extends around the front of the steam generator for a carrying strap (not shown). The casings are cutaway 18 behind the rebate to provide a space for accommodation of the water reservoir. The lower casing has a front underneath recess 19 for a pivoted angle fitting 24 for the hose.

Referring now in more detail to FIG. 2, the water reservoir can be seen to have a filling spout 33, provided with an O-ring 330, which engages with an annular feature (not shown) on the underside of the cover plate 12 for sealing the reservoir in use. Extending forwards from the spout 33 is a water outlet nozzle 34 having an O-ring (not shown) for sealing in a connector moulding 35. Inside the spout, the nozzle is adapted with a rimmed inlet 36 for connection of a weighted tube (not shown) for drawing water from the lowest portion of the reservoir, according to its orientation. The reservoir can be disconnected from the generator for filling by grasping at a pair of indents 37 in its rear wall. The bottom of the reservoir is contoured to clear a ridge 38 in the lower casing 2 at which a mains electricity cable (not shown) passes into the generator to a terminal block 51.

The connector moulding 35 has rims 39 for engaging on opposite sides of an end wall 200 of the casing at a recess for the connector. Thus the moulding is located for sealing connection of the nozzle 34 to it when the reservoir is connected back to the generator after filling. The moulding has two bored-through projections 40,41. The upper of these has a rimmed outlet 42 for a sealing connection of a tube (not shown) to a pump 52. This is a mains frequency diaphragm pump.

The pump's delivery tube 53 is connected to an inlet spout 54 of a boiler 55, the spout being in an end plate 56 casting of the boiler. The latter has a main casting 57, the castings being of aluminium. The main casting is generally rectangular, with one rounded end 58 and a central cylindrical recess 59. Pressed into U-shaped grooves 60 in the front and back faces of the casting are U-shaped heating elements 61, which are wired in series.

The end plate 56 of the boiler has a horizontal tongue 560 which is a close fit in the cylindrical recess, save for leaving a gap at the remote end of the recess. This defines a flow passage in the boiler from the inlet spout 54, along below the tongue, round its end and back above it to a normal outlet spout 58. A tube (not shown shown in FIGS. 2 and 3) is connected to this which passes into the front angle fitting 23 of the hose 22. A further outlet or safety spout 59 is provided for another tube leading to the lower projection 41. This has a disc 62 at its end, with an opening 63 to atmosphere. The tube (not shown) is a tight fit on the disc and clipped to the projection at its root against the main part of the connector moulding. The arrangement is normally pressure tight, but if the pressure in the boiler should reach an unsafe level, the tube will expand radially at the disc and steam will be released between the disc and the wall of the tube.

The boiler is sealed by an O-ring (not shown) clamped between the castings under the action of screws (not shown) engaging with upper and lower lugs on the endplate 56. For mounting of the boiler with minimal heating of the casing, it is provided with a stainless-steel, poor-conductor bracket fixed to the lower casing 2 with minimal physical contact. On its front side opposite from the mounting plate, the boiler casting carries three thermistor operated controllers 64,65,66, held in tight thermal contact with the main casting by a bar 67. The first controller 64 is normally open below 130° C., and closed above this temperature. The second controller 65 is a two temperature device, which starts initially closed and opens at 175° C. It closes again at 140° C. The third controller 66 is initially closed and opens irreversibly at 225° C.

The final main component inside the casing is a switch 69. It is a microswitch for the pump 52. It is actuated by a pneumatic actuator 690 positioned underneath it to its inboard side. The actuator is connected by a pipe 25, not shown in FIGS. 2 & 3, but visible in FIG. 8 in the handle 21. The handle carries a second button 26 arranged over an activation bellows unit 27 connected to the pipe 25. The handle also carries at its distal end a steam connector fitting 28, having an O-ring 29. Connection will be described in more detail below.

When the unit is switched on via the ON/OFF switch 10, power is applied to the boiler heating elements 61 and to one of the LEDs 8 to indicate that the boiler is being heated. The switch incorporates its own power-on LED 70. When but not before the temperature reaches 130° C., the first controller switches power to the microswitch 69 and to the second LED 9, the latter to indicate that the steam generator can be used. Action on the button 26 then switches the microswitch, by action of pneumatic pressure from the bellows 27 to the actuator 690. The pump 52 then delivers water to the boiler. This now being well above the boiling point of water generates steam, which flows along the tube in the hose to its end 30 sealed to the inner end of the connector 28. As long as the second button 26 is depressed, steam will flow from the connector.

The pump is rated to deliver just less water than the capacity of the boiler heating elements to boil continuously, whereby the boiler's temperature gradually rises. When it reaches 175° C., the second controller switches off the heating elements. The temperature of the boiler then cycles between 175° C. and 140° C., in fact continuously whether steam is being used or not.

The boiler has to heat the water from ambient temperature and then supply the latent heat of vaporisation. The latter is considerably greater. The result is that a nominal 2KW boiler can vaporise approximately 0.75 gm per sec of water, i.e. 45 gm/minute. The preferred pump, Evolution Micro-Pump NME4 from Ulca srl of Retorbido 2750 in Italy, has an initial capacity of approximately 1.6 cc/sec against a pressure of 4 bar. This is in excess of the boiler's rating, but the boiler being heated well above 100° C. the initial flow of the pump can be vaporised. Then the flow of the particular pump used falls below 1.6 cc/sec or 1.6 gm/sec to approximately 0.6 to 0.7 gm/sec. This is within the continuous rating of the boiler. The reservoir has a capacity of 750 cc. This gives a continuous operating time of approximately a quarter of an hour.

It should be noted that although the hose 22 is described as such, it comprises an outer corrugated plastics material sleeve, with the steam tube and the pneumatic tube accommodated within the sleeve. The sleeve is secured to the handle 21 at one end and to the angled fitting 24 at the other end. The hose enables the caddy with the casing to be dragged on the wheels and a skid (not shown) under the front of a caddy about to be described.

Referring now to FIG. 10, there is a shown the caddy 101 for the steam generator just described. Generally the caddy provides a platform 102 for the steam generator and a pair of wheels 103 for its manoeuvre. The platform has a pair of upstanding webs 104, which engage on the outside of the lower casing 2, with lips engaging in the strap rebate 17. A resilient flap 105 hinged 106 at its front end is provided above and behind the wheels for holding the casing against the webs 104, which taper slightly, the flap being provided with pawls 107 engaging the back of the lower casing. Depression of the flap at its back end 108 releases the pawls for withdrawal of the casing from the caddy. Outside the webs 104, a pair of wings 109 are provided for the hose to be wound inside and around the casing.

A recess 110 is provided at the front of the caddy for a power cable plug (not shown). The recess has a socket 111 at its bottom. The centre 1010 of the caddy is open for storing tools such as the smoothing tool 1011 shown in FIG. 13. It has a socket 1012 for receiving the nose 210 of the handle, the socket and the nose having complementary non-circular cross-sectional shapes. Also it has an aperture 1013 for receiving the spring loaded button 23 of the handle. Thus the tool is held fast on the handle. Internally, the tool has a socket 1014 for making steam tight connection with the handle's steam connector fitting 28.

Also stored are a pair of rigid hose extensions 112, along each side of the caddy (see FIGS. 9 to 12). At one end they are provided with resilient buttons 113 such as the button 23 on the handle and with steam connectors 114 with O-rings. The other end of each extension is open with a shape 115 complementary to that of the nose of the handle, for irrotationally receiving it or the end of another extension. When the nose of the handle is inserted, its button 23 engages in an aperture 116 in the shaped end 115. Further a steam socket 117 complementary to that of the steam connector 28 is provided. Thus the handle can be irrotationally and steam tightly connected to one of the extensions and it can be connected to the next. When the rigid hose extension are accommodated on the caddy, their buttons 113 engage in recessed apertures 118 on respective sides of the hinged flap 105. Internally the extensions have at one end a moulding 119 having the steam connector 114 and to the other end a complementary moulding 120 with the socket 117. These mouldings are interconnected by a tube 121 forming the internal wall of the extension spaced by an air gap 122 from the outer wall 123.

The socket 111 is complementary to the shape of the extensions, whereby these can be temporarily stood up in the caddy for ease of access and temporary support of miscellaneous items.

In an underneath cavity 80, between the boiler and the reservoir, the casing houses a number of small auxiliary tools such as the brush 81—see FIG. 14. It clips on to the steam connector 28 and is retained frictionally by the O-rings 29, the tool being of the same outside dimension as the nose 210 of the handle.

The invention is not intended to be restricted to the details of the above described embodiment. For instance, the bellows in the handle can be replaced by the piston and cylinder device shown in FIG. 15. This has a tapered mouth cylinder 201 connected to a pneumatic tube 202. A piston 203 is arranged to be pushed into the cylinder, with an O-ring 204 then sealing the two. A spring 205 urges the piston out. In the quiescent state, the O-ring is out of engagement with the cylinder, whereby any pressure build-up in the pneumatic tube, as from heating from the steam, is released when the button 205 is released. Thus the pump and the supply of steam is immediately stopped on release of the button. 

1. A steam generator comprising: a water reservoir, a pump for pumping water from the reservoir, a flash steam boiler for boiling water pumped from the reservoir to produce steam, a steam supply hose leading from the boiler, a handle at the distal end of the hose, and means on the handle for activating the pump, to cause a flow of steam from the distal end of the hose.
 2. A steam generator according to claim 1, wherein the pump activating means is an electrical switch, the pump being an electrical pump.
 3. A steam generator according to claim 1, wherein the pump activating means is non-electric.
 4. A steam generator according to claim 3, wherein the pump activating means is adapted to send a non-electrical signal to a switch for switching electrical power to the pump.
 5. A steam generator according to claim 4, wherein the pump activating means is adapted to send a pneumatic signal to the pump switch.
 6. A steam generator according to claim 5, wherein the pump activating means on the handle is a manually operated pneumatic system.
 7. A steam generator according to claim 6, wherein the pump activating means is arranged to be normally open to atmosphere when in the quiescent state.
 8. A steam generator according to claim 6, wherein the pump activating means is a small bellows device on the handle.
 9. A steam generator according to claim 7, wherein the pump activating means is a small bellows device on the handle and the bellows device has an aperture closed on activation.
 10. A steam generator according to claim 6, wherein the pump activating means is a piston and cylinder on the handle and a bellows for actuating a microswitch in a body of the generator.
 11. A steam generator according to claim 7, wherein the pump activating means is a piston and cylinder on the handle and a bellows for actuating a microswitch in a body of the generator.
 12. A steam generator according to claim 11, wherein the piston and cylinder device has a counter-bore at its end remote from the electrical switch, the arrangement being such that the piston is out of pneumatic sealing of the cylinder in its quiescent state, hence releasing any over-pressure.
 13. A steam generator according to claim 4, wherein the steam supply hose and a pneumatic tube from the hose handle to the pump switch are both enclosed within an outer wall.
 14. A steam generator according to claim 1, wherein the flash steam boiler incorporates a first thermostatic controller for switching an electrical heater for the boiler—ON at a lower temperature and OFF at a higher temperature.
 15. A steam generator according to claim 14, wherein the lower and higher temperatures are tens of Centigrade degrees apart, with the lower temperature being tens of degrees above 100° C.
 16. A steam generator according to claim 15, wherein the lower temperature is approximately 140° C. and the upper temperature is approximately 175° C.
 17. A steam generator according to claim 14, wherein the boiler includes a second thermostatic controller for inhibiting operation of the pump until the boiler is at or close to its operating temperature or at least the lower of the temperatures of the first thermostatic controller.
 18. A steam generator according to claim 17, wherein the second thermostatic controller is adapted to maintain the pump switched OFF until the boiler is a temperature tens of Centigrade degrees above 100° C. but lower than the lower temperature of the first thermostat.
 19. A steam generator according to claim 18 as appendant to claim 15, wherein the lower temperature is approximately 140° C. and the upper temperature is approximately 175° C. and the boiler inhibition temperature is approximately 130° C.
 20. A steam generator according to claim 14, wherein the pump is arranged to be inhibited below the lower temperature of the first thermostatic controller.
 21. A steam generator according to claim 17, wherein the boiler includes a third thermostat for isolating the boiler in the event of the temperature of the boiler reaching a temperature tens of Centigrade degrees above the higher temperature of the first thermostat.
 22. A steam generator according to claim 21, wherein the boiler isolation temperature is approximately 225° C.
 23. A steam generator according to claim 1, wherein the boiler is constructed with a central, cylindrical chamber divided longitudinally by a dividing tongue.
 24. A steam generator according to claim 23, wherein the boiler is an aluminium casting carried on a stainless steel mounting plate.
 25. A steam generator according to claim 23, wherein a water inlet is provided on one side of the tongue and a steam outlet is provided at the other side, the inlet and outlet being at one end of the tongue and communication around the tongue being provided at the other end of the tongue.
 26. A steam generator according to claim 25, wherein a further safety valve outlet, is provided at the other side of the tongue.
 27. A steam generator according to claim 26, wherein the safety valve is an obturator in an elastomeric tube connected to the safety valve outlet, the tube being vented on the side of the obturator remote from the safety valve outlet, excess pressure steam being vented on expansion of the tube around the obturator, allowing the steam to flow past the obturator.
 28. A steam generator according to claim 1, wherein the wattage of the boiler and the capacity of the pump are matched whereby the pump delivers no more water than the boiler can continuously evaporate.
 29. A steam generator according to claim 28, wherein the boiler is rated at 2000 Watts and the pump is adapted to deliver 1.6 cubic centimetres per second of water.
 30. A steam generator according to any preceding claim, wherein the preferred pump is a mains frequency diaphragm pump.
 31. A steam generator according to claim 1, including: a casing for the pump and the boiler, a casing handle formed to receive releasably the hose handle and release means on the hose handle, discrete from the pump activation means, for releasing the hose handle from the casing handle.
 32. A steam generator according to claim 31, including a caddy, the caddy and the casing being formed complementarily for accommodation of the caddy on the casing, a latch preferably being provided for normally retaining the casing on the caddy.
 33. A steam generator according to claim 32, in combination with one or more steam application tools and/or one or more hose extensions, the tool(s) and the hose extension(s) being formed: in like manner to the casing handle to receive releasably the hose handle and with an inner steam connection socket, held connection with a steam connector on the handle, whilst a respective one of the tool(s) and the hose extension(s) receives the hose handle.
 34. A steam generator according to claim 33, wherein the hose extensions have double walls, with an air gap between an outer wall and an inner steam conduit: the outer wall having release means in like manner to the release means on the hose handle and the inner steam conduit having the inner steam connection socket at one end and a steam connector at the other end, also in like manner to the steam handle for connection to another extension or tool.
 35. A steam generator according to claim 33, wherein the caddy has a compartment for storage of the tool(s).
 36. A steam generator according to claim 34, wherein the caddy has a respective receptacle for the hose extensions, the receptacle(s) being formed in like manner to the casing handle to receive releasably the extension(s) with their release means.
 37. A steam generator according to claim 33, wherein the caddy has a socket for upright support of the hose extension(s), whereby an item of clothing can be supported therefrom for steaming.
 38. A steam generator according to claim 31, wherein the casing has a compartment for storage of auxiliary tools adapted to connect to the hose without use of the release means.
 39. A steam generator according to claim 31, wherein the water reservoir is detachable from the casing for filling with water, a latch being preferably provided for retaining the reservoir on the casing.
 40. A steam generator according to claim 39, wherein the reservoir is provided with a sealable lid whereby the generator can be used at varying orientations the latch being integrated with the sealable lid.
 41. A steam generator according to claim 40, wherein the reservoir and the casing are provided with complementary water connections for leading water from the reservoir to the pump.
 42. A steam generator according to claim 31, wherein the casing is provided with a carrying strap, for carrying of the steam generator—separate from the caddy where provided—for use. 